EP-4738991-A1 - CONTROL SYSTEM FOR INDUCTION HEATING

Abstract

A system for controlling an induction cooking apparatus includes resonant loads each having an induction coil of said induction cooking apparatus, switching circuitry including a shared half-bridge, and a plurality of secondary half-bridges each cooperating with the shared half-bridge to form a plurality of full-bridge inverters. Control circuitry is configured to determine a plurality of target power levels including a target power level for each one of the plurality of resonant loads, calculate a switching frequency common to the shared half-bridge and the plurality of secondary half-bridges based on the comparison of the target levels, generate a plurality of control signals each for application to a half-bridge of the plurality of secondary half-bridges, calculate a phase displacement for each of the plurality of control signals, and determine a maximum current through the shared half-bridge independent of an orientation of the phase displacement for each of the plurality of control signals.

Inventors

• Barbati, Mario
• Baldo, Salvatore
• GALLIVANONI, Andrea

Assignees

• Whirlpool Corporation

Dates

Publication Date

20260506

Application Date

20251030

Claims (12)

1. A system for controlling an induction cooking apparatus (10), comprising: a plurality of resonant loads (11, 11a, 11b) each having an induction coil (12, 12a, 12b) of said induction cooking apparatus (10); switching circuitry (13) including a shared half-bridge (14) and a plurality of secondary half-bridges (16, 16a, 16b) each cooperating with the shared half-bridge (14) to form a plurality of full-bridge inverters, wherein each of the plurality of full-bridge inverters is configured to selectively power a resonant load (11, 11a, 11b) of the plurality of resonant loads (11, 11a, 11b); and control circuitry configured to: determine a plurality of target power levels including a target power level for each one of the plurality of resonant loads (11, 11a, 11b); compare the plurality of target power levels; calculate a switching frequency common to the shared half-bridge (14) and the plurality of secondary half-bridges (16, 16a, 16b) based on the comparison of the target power levels; generate a plurality of control signals each for application to a half-bridge of the plurality of secondary half-bridges (16, 16a, 16b); calculate a phase displacement for each of the plurality of control signals; determine a maximum current through the shared half-bridge (14) independent of an orientation of the phase displacement for each of the plurality of control signals; and adjust the orientation of the phase displacement for each of the plurality of control signals to reduce the maximum current.
2. The system of claim 1, wherein each control signal is a pulse-width modulated (PWM) signal representative of the switching frequency, and wherein the PWM signal for the shared half-bridge (14) defines a rising edge (96) of a pulse of the PWM signal to the shared half-bridge (14).
3. The system of claim 2, wherein the orientation includes one of a time-shift ahead and a time-shift delay from the rising edge (96).
4. The system of either one of claims 2 or 3, wherein the plurality of resonant loads (11, 11a, 11b) is a first resonant load (11a) and a second resonant load (11b), and wherein the control circuitry is configured to shift a first control signal ahead of the rising edge and a second control signal behind the rising edge (96).
5. The system of any one of claims 1-4, wherein the plurality of secondary half-bridges (16, 16a, 16b) is a first half-bridge (16a) and a second half-bridge (16b) each including a high-side secondary switch (76) and a low-side secondary switch (78).
6. The system of claim 5, wherein the shared half-bridge (14) includes a primary high-side switch (72) and a primary low-side switch (74).
7. The system of either one of claims 5 or 6, wherein the secondary switches (76, 78) are IGBTs and the control circuitry includes a controller (24) that controls the IGBTs via the control signals to adjust the orientation of at least some of the phase displacements.
8. The system of any one of claims 1-7, wherein the control circuitry is configured to: select from a plurality of orientation patterns a target orientation pattern for the plurality of control signals to provide a lowest current peak to achieve the plurality of target power levels at the switching frequency.
9. The system of any one of claims 1-8, further comprising: a shared node (35) electrically connecting each of the plurality of resonant loads (11, 11a, 11b) to the shared half-bridge (14).
10. The system of any one of claims 1-9, wherein calculation of the switching frequency includes identifying an operating frequency for the highest target power level and assigning the operating frequency to the switching frequency.
11. The system of any one of claims 1-10, wherein the control circuitry is configured to apply the plurality of control signals.
12. The system of any one of claims 5-7, wherein the control circuitry is configured to: in response to determining that the target power levels are equal, offset activation of the high-side secondary switch (76) of the first half-bridge (16a) relative to activation of the high-side secondary switch (76) of the second half-bridge (16b).

Description

BACKGROUND OF THE DISCLOSURE The present disclosure generally relates to control of induction heating and, more specifically, to controlling activation signals for inverters of an induction heating system. SUMMARY OF THE DISCLOSURE According to one aspect of the present disclosure, a system for controlling an induction cooking apparatus includes a plurality of resonant loads each having an induction coil of said induction cooking apparatus, switching circuitry including a shared half-bridge, and a plurality of secondary half-bridges each cooperating with the shared half-bridge to form a plurality of full-bridge inverters. Each of the plurality of full-bridge inverters is configured to selectively power a resonant load of the plurality of resonant loads. Control circuitry is configured to determine a plurality of target power levels including a target power level for each one of the plurality of resonant loads, compare the plurality of target power levels, calculate a switching frequency common to the shared half-bridge and the plurality of secondary half-bridges based on the comparison of the target levels, generate a plurality of control signals each for application to a half-bridge of the plurality of secondary half-bridges, calculate a phase displacement for each of the plurality of control signals, determine a maximum current through the shared half-bridge independent of an orientation of the phase displacement for each of the plurality of control signals, and adjust the orientation of the phase displacement for each of the plurality of control signals to reduce the maximum current. According to another aspect of the present disclosure, a system for controlling an induction cooking apparatus includes a plurality of resonant loads each having an induction coil of said induction cooking apparatus, switching circuitry including a shared half-bridge, and a plurality of secondary half-bridges each cooperating with the shared half-bridge to selectively power a resonant load of the plurality of resonant loads. Control circuitry is configured to calculate a switching frequency common to the shared half-bridge and the plurality of secondary half-bridges, generate a plurality of control signals each for application to a half-bridge of the plurality of secondary half-bridges, calculate a phase displacement for each of the plurality of control signals, determine a maximum current through the half-bridge independent of an orientation of the phase displacement for each of the plurality of control signals, and adjust the orientation of the phase displacement for each of the plurality of control signals to reduce the maximum current. According to yet another aspect of the present disclosure, a system for controlling an induction cooking apparatus includes a plurality of resonant loads each having an induction coil of said induction cooking apparatus, switching circuitry including a shared half-bridge, and a plurality of secondary half-bridges each cooperating with the shared half-bridge to form a plurality of full-bridge inverters, wherein each of the plurality of full-bridge inverters is configured to selectively power a resonant load of the plurality of resonant loads. Control circuitry is configured to calculate a switching frequency common to the shared half-bridge and the plurality of secondary half-bridges, generate a plurality of control signals each for application to a half-bridge of the plurality of secondary half-bridges, calculate a phase displacement for each of the plurality of control signals, determine a maximum current through the half-bridge independent of an orientation of the phase displacement for each of the plurality of control signals, and adjust the orientation of the phase displacement for each of the plurality of control signals to reduce the maximum current. These and other features, advantages, and objects of the present disclosure will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: FIG. 1 is a top-perspective view of an induction cooktop;FIG. 2 is a simplified block diagram schematic of a heating circuit for an induction cooking apparatus;FIG. 3 is a detailed electrical schematic of a heating circuit for an induction cooking apparatus;FIG. 4 is a timing diagram of activation signals, voltages, and currents for a heating circuit with phase displacements applied for controlling power output;FIG. 5 is a timing diagram of activation signals, voltages, and currents for a heating circuit with phase displacements and phase orientations adjusted for controlling power output; andFIG. 6 is a flow diagram of a method for controlling an induction cooking apparatus according to one aspect of the present disclosure. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles described herein. DETAI